Aqueous highly alkaline hair relaxing or straightening compositions are known in the art. These compositions usually have a highly alkaline pH, i.e., a pH of about 12 to about 14, due to the presence of an alkaline hair relaxing material. For example, a water-soluble inorganic lye or non-lye caustic base, such as alkali or alkaline earth hydroxide or a relatively strong organic base such as guanidine, guanidine hydroxide or quaternary ammonium hydroxide is used.
Aside from their causticity, one principal disadvantage of highly alkaline hair relaxers is that they leave the hair in a brittle state and harsh to the touch. Another disadvantage is that highly alkaline compositions containing all or a portion of the active alkaline hair relaxing agent are difficult to compound in the form of phase-stable emulsified creams. This instability limits the effective inclusion of useful hair conditioning agents. Thus, there is a long-standing need and desire for a conditioning hair relaxing system.
Modern highly alkaline hair relaxers are preferably of the type commonly called "no-base" hair relaxers. The term "no-base" means that the scalp need not be coated with a protective oleaginous base such as petrolatum, mineral oil and lanolin, before applying the highly alkaline hair relaxer.
One type of no-base hair relaxer formulation contains as the sole active hair straightening agent an alkali metal hydroxide, typically a caustic base, such as sodium hydroxide, potassium hydroxide or lithium hydroxide. When a relatively low active level of about 1.5 to about 2.5 weight percent of caustic base is used, the protective base is applied only to the hairline to protect the skin around the forehead, ears and neckline. Such no-base formulations have some of the protective oleaginous material emulsified in an aqueous composition, preferably in the form of a viscous cream, and are supplied in a "single product" kit.
Another no-base hair relaxer formulation is commonly called a "no-lye" hair relaxer. With a no-base, no-lye relaxer, a protective base need not be applied to the scalp and may not need to be applied to the hairline. The term "no-lye" as used herein means that the active hair straightening agent is an organic chemical base instead of inorganic caustic base. In commercial practice, the relatively strong organic chemical base, guanidine is usually present in the form of guanidine hydroxide. However, guanidine hydroxide is not generally stable for long periods in aqueous solutions. Consequently, it must be prepared fresh just before using.
Guanidine hydroxide is generally prepared by reacting an inorganic chemical base such as an alkaline earth hydroxide with an aqueous solution of a salt of the strong organic chemical base guanidine where the anion of this salt is capable of being precipitated by the cation of the alkaline earth hydroxide. In commercially available products of this type, the guanidine hydroxide is generally prepared using guanidine carbonate and calcium hydroxide.
When such a no-lye hair relaxer is commercially used, the product is supplied as a two-part kit. One part contains the guanidine carbonate in substantially liquid form and is commonly called the "activator." The other part contains relatively high amounts of about 4 to about 7 percent calcium hydroxide emulsified in a cosmetic cream base. Prior to using, the consumer or beautician mixes the cream and activator portions of the kit together. The resulting no-lye hair relaxer is then relatively promptly (preferably within 24 hours) applied to the hair.
Some great strides have been made in formulating no-base hair relaxer compositions by incorporating conditioning agents in the highly alkaline emulsions so that the straightened hair has a better feel after such a treatment. However, highly alkaline emulsion products containing sufficient inorganic alkaline material to provide all or a portion of the active hair relaxing agent, as well as conditioning agent, are difficult to compound. These emulsions require much care particularly during preparation on a commercial scale, and separate or de-emulsify relatively quickly on aging thereby limiting their commercially useful lifetime.
Most no-base hair relaxer cream products are preferably aqueous emulsions in which water is the continuous phase, i.e., oil-in-water emulsions, because they are easier to rinse from the hair. Instability or de-emulsification results in a destabilized cream product having two distinctly visible phases. While such destabilized cream products may be used, they must be remixed before using in an attempt to assure the user that the active ingredients are at the proper levels in the portion being used. However, such mixing, even though done thoroughly by hand, does not, in fact, give the user consistent results with such products. Improper mixing can also cause skin irritation or result in increased hair breakage. Product destabilization and resulting consumer dissatisfaction are among the chief complaints in the industry. Thus, a phase-stable cream is needed that shows substantially no visible separation into distinct phases on storage aging.
Cationic compounds, in particular, are generally considered to improve the condition of hair. The terms "cationic conditioning agent" and "cationic conditioner" as used herein refer to substantially water-soluble cationic compounds which under certain circumstances are substantive to hair. It is commonly recognized that substantive cationic conditioning compounds can effectively leave the hair feeling silky, soft and more manageable with less static fly-away, characteristics which are desirable attributes of hair conditioners.
During a hair-relaxation treatment, the hair can be most easily penetrated by a cationic conditioner present in the relaxer. The hair is swollen during relaxation, under the action of the alkali, and the cuticles on each hair shaft are sufficiently raised so that the conditioner can find entry between them into the hair shaft. In contrast, after the relaxer is rinsed off, the hair deswells and the cuticles flatten. Conditioners applied at this stage to the deswollen hair cannot penetrate the hair shafts to the same extent and are less effective in achieving conditioning.
Most of the strongly alkaline hair relaxers for home use are sold in kits containing one or more conditioners packaged in a separate containers for application to the hair either before applying the relaxer or after the relaxation process. Such conditioning, performed as a separate step, is inconvenient and is only partially effective in overcoming the harshness imparted by the alkaline treatment. The inclusion of water-soluble polymeric cationic compounds into a strongly alkaline hair relaxer composition is particularly desirable to counteract the harshness imparted by the alkalinity. However, some water-soluble cationic polymers are not useful ingredients for strongly alkaline compositions. Some water-soluble cationic polymers, when incorporated into strongly alkaline emulsion cream compositions, especially in the pH range from about 12.5 to about 13.8, can cause phase destabilization of the emulsion during storage aging. Other water-soluble cationic polymers which do not destabilize the emulsion may, nevertheless, lose their own effectiveness to condition hair under the highly alkaline pH required for relaxation.
Until now, some success in achieving a conditioning hair-relaxer system was met by incorporating certain useful water-soluble polymeric quaternary nitrogen conditioning agents useful as a component of the highly alkaline no-lye cream base portion of a two-product kit. For example, the use of a quaternary nitrogen-containing polymer prepared by polymerizing and co-polymerizing a diallyldimethylammonium salt is disclosed in co-assigned U.S. Pat. Nos. 4,175,572 ('572), 4,237,910 ('910), 4,390,033 ('033), 4,524,787 ('787) and in co-assigned copending U.S. patent application Ser. No. 173,318 abandoned in favor of filing continuation application Ser. No. 399,385, now issued as U.S. Pat. No. 4,950,485. The disclosures of each of the foregoing are incorporated herein by reference. Another useful water-soluble quaternary nitrogen polymer, a copolymer of methylvinylimidazolium chloride and vinylpyrrolidone, is disclosed in co-assigned U.S. patent application Ser. No. 763,519 and related French Patent publication No. 2,585,947A, both now abandoned, the disclosures of which are also incorporated herein by reference.
Problems of product instability are also caused by the presence of relatively high amounts of water-insoluble oleaginous ingredients which must be co-emulsified with the alkaline material. Oleaginous materials, such as petrolatum and lanolin, are desirable in no-lye cosmetic cream bases to maintain the benefits of a no-base procedure. But the water-insoluble character of these materials greatly decreases the chances of successfully formulating a phase-stable cream, especially a highly alkaline cream containing inorganic alkaline material. These problems are magnified when a formula is scaled up for the production of commercial quantities.
Part of the foregoing problems were also overcome in the previously mentioned '033 and '910 patents of our assignee, by using certain lipophilic organically-modified hectorite clay gellants. Those clay gellants were disclosed for stabilizing highly alkaline no-base hair relaxer compositions containing relatively high amounts of oleaginous material against phase separation. Commercial hair relaxer products embodying the principles disclosed in these patents have been marketed. However, compounding a phase-stable cream, even with the above disclosed hectorite clay gellant, requires considerable care to substantially uniformly disperse the disclosed hectorite clay gellant.
Moveover, relatively high amounts (about 8 to about 12 weight percent) of the hectorite clay gellant are generally required to achieve a relatively stiff viscous cream. For example, the '033, the '910 and the '572 patents all disclosed that at below about 2 weight percent of the hectorite clay gellant, little phase stability improvement was noted and the resulting creams were relatively soft. Thus, while generally elegant, relatively stiff viscous creams can be obtained by practicing the emulsion stabilizing principles taught in the '033 and '910 patents, the products are relatively costly to manufacture commercially from the standpoints of costs for labor, materials and energy.
No-base hair relaxers are desirably formulated as emulsified viscous creams so that once applied to the user's hair, they will not drip onto the skin or into the eyes of the person receiving a hair straightening procedure. The cosmetic cream base portion of a no-lye hair relaxer kit must also mix easily with the liquid activator portion without thinning to a soft runny cream.
A commercially desirable conditioning hair-relaxing system, therefore, would utilize a phase-stable, viscous no-base hair relaxer cream, effect conditioning while relaxing the hair, be easy to remove from the hair at the end of the straightening or relaxer procedure and provide a substantive conditioned effect to the relaxed hair.
The present invention provides for such a conditioning hair-relaxing system characterized by a conditioning activator for a no-base, no-lye hair relaxer, and for a phase-stable viscous cosmetic cream base for use therewith in no-base hair relaxer systems and methods of preparing same.